Cocaethylene is a pharmacologically active homolog of cocaine, formed by transesterification of cocaine in the presence of alcohol. This randomized, placebo-controlled, double-blind study has been undertaken to examine the physiological and subjective effects and pharmacokinetics of intravenously administered cocaethylene in humans using cocaine as a comparator. Cocaine-dependent participants randomly receive one study drug or placebo, during each experimental session which occurs on separate days. Interim analysis of the first 6 subjects to complete the study shows that while drug plasma concentrations for equivalent doses of cocaine and cocaethlyene do not differ, cocaethylene appears to be less potent in its ability to elevate heart rate. Similar results were detected for subjective measures ("cocaine high", "rush", "stimulated" and "good drug effects"). All active drug conditions produce significant increases in systolic blood pressure relative to placebo, but no significant effect on diastolic blood pressure has been observed thus far. Cocaethylene appears to have a longer elimination half-life than cocaine. The findings from this study to date confirm those of previous studies which show that cocaethylene is less potent that cocaine in humans. This study continues to enroll subjects and a second analysis of differences in responses to cocaine and cocaethylene by gender will be completed.